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A domain name server (DNS) converts domain names into Internet protocol (IP) addresses. Domain name servers can be thought of as the Internet's equivalent of a phone book. As they maintain a directory of domain names and translate them into IP addresses, these mappings allow a computer to locate a website and a user to access a website.
One domain name server example is the domain name www.whitehatsec.com. Through DNS, it is converted to the IP address 18.104.22.168.
When the user submits a web address like www.whitehatsec.com a quick search is made to see if the site was visited before, if it is located in the DNS cache the user will then be brought to the site. If no DNS record is found the query is sent to the local DNS server. The local DNS server which is usually the Internet provider’s server and is often called a resolving name server. A name server is a special type of server that keep all DNS records of your domain names.
If it cannot be located in the resolving name server it is then forwarded onto the root name server to try and find the DNS record. Root name servers are used for storing DNS data and keeping the system running smoothly. Once the requested DNS record (this is the site we requested) is found this information is then cached on your computer.
Now that the DNS record is located, we can now connect to the server which the site is stored in as the DNS includes the IP address the user needs to connect to the site.